For a simpler evaluation of military power, we turned to the Global Firepower Index, a ranking of 106 nations based on more than 50 factors including overall military budget, available manpower, and the amount of equipment each country has in its respective arsenal, as well as access to natural resources.

The index focuses on quantity, ignoring significant qualitative differences — North Korea's 78 submarines, for instance, aren't exactly state of the art. It also does not factor in nuclear stockpiles, which are still the ultimate trump card in geopolitics. And it doesn't penalize landlocked nations for lack of a standing navy.

We've created a chart to compare the top 35 militaries according to the Global Firepower Index. The ranking was released in April (before events like the Russian invasion of Eastern Ukraine in August, ISIS's blitz through Iraq, and the flare-up between Israel and Hamas) and involves a complex set of data that is subject to ongoing adjustments and corrections.

Russia, meanwhile, has increased its arms spending by $88 billion and plans to "modernize" its arsenal.

Aircraft carriers are key, and very few countries have one.

Aircraft carriers contribute greatly to a country's overall military strength. These massive vessels allow nations to project their force far beyond their borders and across the entire face of the globe. They're essentially mobile naval and air force bases. Aircraft carriers can also carry drones, which significantly change the global surveillance game.

The US's absolute monopoly on super-carrier vessels significantly boosts the country's forward operating power. The US has deployed an aircraft carrier toward the Persian Gulf to bolster its sea and air power before possible strikes against ISIS in Iraq. Russia has previously deployed an aircraft carrier to the Mediterranean to display its seriousness in propping up Assad in Syria.

North Korea's useless submarines.

An anomaly in the Global Firepower index is North Korea's ranking as a world leader for submarines. And while it's true that Pyongyang commands the largest submarine fleet on earth, most of these vessels are unusable.

A third of North Korea's subs are noisy diesel-powered Romeos, which have been obsolete since 1961. These submarines have a weapons range of only four miles, whereas a modern US submarine has a range of 150 miles. This fleet is unsophisticated but still durable, according to the US Department of Defense.